Adhesive Offering Z-Axis Conductivity, Stretchability and Manufacturing Scalability for LED Electroactive Light Sheets

A. Stemmermann, D. Balder, M. Stemmermann, P. Lall
SunRay Scientific LLC,
United States

Keywords: low-cost, fine pitch, high yield, stretchable, reliable, shock tolerant


New product demands call for new solutions. Globally, the electrically conductive adhesives market has seen more than 40 new product launches in the last three years. Clearly certain needs are as yet unmet. Among those unmet needs is efficient bonding between conformal substrates and rigid components for flexible hybrid electronics (FHE). Fitness trackers, sleep monitors and augmented-reality glasses illustrate the well-known starting point for monitoring systems. Less well-known are the advanced textiles for stretchable, wearable devices to protect military personnel, firefighters, and to monitor neonates (premature babies). Aerospace and automotive sectors also have demanding applications requiring flexibility FHE solutions. Advances in sensors, communication chips and artificial intelligence enable these designs to be light weight and untethered. However, these devices, being rigid, require a connection technology that can absorb the stresses caused by vibration, bending, and stretching. The interconnection must be robust, reliable, structurally capable, while providing a cost-effective high-density interconnect solutions that overcome limitations of conventional solder; particularly for non-planar, conformal integration that enables rapid prototyping and high-volume scalability. Emerging as a solution for FHE products manufacturing is ZTACH® Anisotropic Conductive Epoxy (ACE). Having already gone through years of testing for semiconductor device manufacturer and matched with encapsulation technology that enhances its performance, ZTACH® ACE is being rigorously tested for FHE applications. ZTACH® is applied as a paste. It uses magnetically induced self-assembly of Z-Axis wires in a flexible, durable matrix to form the interconnect in seconds. This interconnect technology was chosen for this surface-mount Light Emitting Diodes (LEDs) project because it allows for pressure-less assembly, provides adhesion to an unusually wide range of materials, and fine pitch reliability. Using a test vehicle for LED Electro SMT Light Emitting Diodes (LEDs) bonded to a flexible organic substrate, ZTACH® ACE is shown to provide structurally robust electrical connection. Validation testing is performed in parallel with the against same test vehicle utilizing traditional interconnect materials such as solder.